1. Field of the Invention
The present invention relates to a process for preparing 3- and 4-formyltricyclo-[5,2,1,0.sup.2,6 ]-decene-8 by hydroformylating dicyclopentadiene. By virtue of the presence of two double bonds, dicyclopentadiene can form both monoaldehydes and dialdehydes when reacted with carbon monoxide and hydrogen in the presence of carbonyl-forming metals of Group VIII of the Periodic System.
2. Discussion of the Prior Art
The preparation of the dialdehyde, namely, the chemical compound tricyclodecane-dialdehyde from dicyclopentadiene, is described in German Pat. No. 928,645. Cobalt compounds yielding cobalt carbonyl hydrogen are used as catalysts in this case, optionally in the presence of metallic cobalt or iron. The conversion is carried out at 140.degree. C. and at a synthesis gas pressure of 180 atmospheres.
UK Pat. No. 801,734 describes the use of rhodium-containing catalysts, which are present dissolved in the reaction mixture under the process conditions, for the hydroformylation of dicyclopentadiene. An unsaturated tricyclodecene-monoaldehyde having a structure not described in more detail is obtained in a yield of 68 percent as reaction product under the reaction conditions employed, namely, a temperature of 100.degree. C. and a pressure of approximately 197 atmospheres.
Of the two double bonds in the cyclopentadiene molecule, the double bond in the norbornene ring is generally the more reactive. It is therefore to be expected that hydroformylation will preferentially result in the formation of 8- and 9-formyltricyclo-[5,2,1,0.sup.2,6 ]-decene-3.
It therefore became desirable to provide a process which yields the isomeric compounds 3- and 4-formyltricyclo-[5,2,1,0.sup.2,6 ]-decene-8 in good yields by hydroformylation of the cyclopentene ring.